This is skin. About two hundred and eighty-nine million years old.
It is smaller than a fingernail. It came out of old caves in Oklahoma, and nobody knows whose it was.
Skin almost always rots away. Bone is what usually lasts.
Here, storms washed small animals into the caves. Fine clay buried them.
Then oil, seeping up from deep below, soaked into them.
Magnified, the skin is pebbled, like a crocodile's.
In twenty twenty-six, the same caves gave up a mummy. A small reptile, still in its skin.
This is Captorhinus. Its skin was banded, like an accordion.
Scientists looked inside the rock with neutrons. Its rib cage was there, cartilage and all.
It is the oldest rib cage ever found with its cartilage, built to breathe by moving the ribs.
Scientists think reptiles, birds and mammals inherited this way of breathing.
Skin, ribs, cartilage, all kept in clay and oil for two hundred and eighty-nine million years.
